1 /* $OpenBSD: in6_src.c,v 1.99 2024/04/21 17:32:11 florian Exp $ */
2 /* $KAME: in6_src.c,v 1.36 2001/02/06 04:08:17 itojun Exp $ */
3
4 /*
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 /*
34 * Copyright (c) 1982, 1986, 1991, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 * notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 * notice, this list of conditions and the following disclaimer in the
44 * documentation and/or other materials provided with the distribution.
45 * 3. Neither the name of the University nor the names of its contributors
46 * may be used to endorse or promote products derived from this software
47 * without specific prior written permission.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59 * SUCH DAMAGE.
60 *
61 * @(#)in_pcb.c 8.2 (Berkeley) 1/4/94
62 */
63
64 #include <sys/param.h>
65 #include <sys/systm.h>
66 #include <sys/mbuf.h>
67 #include <sys/socket.h>
68 #include <sys/socketvar.h>
69 #include <sys/ioctl.h>
70 #include <sys/errno.h>
71 #include <sys/time.h>
72
73 #include <net/if.h>
74 #include <net/if_var.h>
75 #include <net/route.h>
76
77 #include <netinet/in.h>
78 #include <netinet/ip.h>
79 #include <netinet/in_pcb.h>
80 #include <netinet6/in6_var.h>
81 #include <netinet/ip6.h>
82 #include <netinet6/ip6_var.h>
83 #include <netinet6/nd6.h>
84
85 int in6_selectif(const struct in6_addr *, struct ip6_pktopts *,
86 struct ip6_moptions *, struct route *, struct ifnet **, u_int);
87
88 /*
89 * Return an IPv6 address, which is the most appropriate for a given
90 * destination and pcb. We need the additional opt parameter because
91 * the values set at pcb level can be overridden via cmsg.
92 */
93 int
in6_pcbselsrc(const struct in6_addr ** in6src,struct sockaddr_in6 * dstsock,struct inpcb * inp,struct ip6_pktopts * opts)94 in6_pcbselsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock,
95 struct inpcb *inp, struct ip6_pktopts *opts)
96 {
97 struct ip6_moptions *mopts = inp->inp_moptions6;
98 struct rtentry *rt;
99 const struct in6_addr *laddr = &inp->inp_laddr6;
100 u_int rtableid = inp->inp_rtableid;
101 struct ifnet *ifp = NULL;
102 struct sockaddr *ip6_source = NULL;
103 struct in6_addr *dst;
104 struct in6_ifaddr *ia6 = NULL;
105 struct in6_pktinfo *pi = NULL;
106 int error;
107
108 dst = &dstsock->sin6_addr;
109
110 /*
111 * If the source address is explicitly specified by the caller,
112 * check if the requested source address is indeed a unicast address
113 * assigned to the node, and can be used as the packet's source
114 * address. If everything is okay, use the address as source.
115 */
116 if (opts && (pi = opts->ip6po_pktinfo) &&
117 !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) {
118 struct sockaddr_in6 sa6;
119
120 /* get the outgoing interface */
121 error = in6_selectif(dst, opts, mopts, &inp->inp_route, &ifp,
122 rtableid);
123 if (error)
124 return (error);
125
126 bzero(&sa6, sizeof(sa6));
127 sa6.sin6_family = AF_INET6;
128 sa6.sin6_len = sizeof(sa6);
129 sa6.sin6_addr = pi->ipi6_addr;
130
131 if (ifp && IN6_IS_SCOPE_EMBED(&sa6.sin6_addr))
132 sa6.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
133 if_put(ifp); /* put reference from in6_selectif */
134
135 ia6 = ifatoia6(ifa_ifwithaddr(sin6tosa(&sa6), rtableid));
136 if (ia6 == NULL || (ia6->ia6_flags &
137 (IN6_IFF_ANYCAST|IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED)))
138 return (EADDRNOTAVAIL);
139
140 pi->ipi6_addr = sa6.sin6_addr; /* XXX: this overrides pi */
141
142 *in6src = &pi->ipi6_addr;
143 return (0);
144 }
145
146 /*
147 * If the source address is not specified but the socket(if any)
148 * is already bound, use the bound address.
149 */
150 if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr)) {
151 *in6src = laddr;
152 return (0);
153 }
154
155 /*
156 * If the caller doesn't specify the source address but
157 * the outgoing interface, use an address associated with
158 * the interface.
159 */
160 if (pi && pi->ipi6_ifindex) {
161 ifp = if_get(pi->ipi6_ifindex);
162 if (ifp == NULL)
163 return (ENXIO); /* XXX: better error? */
164
165 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL);
166 if_put(ifp);
167
168 if (ia6 == NULL)
169 return (EADDRNOTAVAIL);
170
171 *in6src = &ia6->ia_addr.sin6_addr;
172 return (0);
173 }
174
175 error = in6_selectsrc(in6src, dstsock, mopts, rtableid);
176 if (error != EADDRNOTAVAIL)
177 return (error);
178
179 /*
180 * If route is known or can be allocated now,
181 * our src addr is taken from the i/f, else punt.
182 */
183 rt = route6_mpath(&inp->inp_route, dst, NULL, rtableid);
184
185 /*
186 * in_pcbconnect() checks out IFF_LOOPBACK to skip using
187 * the address. But we don't know why it does so.
188 * It is necessary to ensure the scope even for lo0
189 * so doesn't check out IFF_LOOPBACK.
190 */
191
192 if (rt != NULL) {
193 ifp = if_get(rt->rt_ifidx);
194 if (ifp != NULL) {
195 ia6 = in6_ifawithscope(ifp, dst, rtableid, rt);
196 if_put(ifp);
197 }
198 if (ia6 == NULL) /* xxx scope error ?*/
199 ia6 = ifatoia6(rt->rt_ifa);
200 }
201
202 /*
203 * Use preferred source address if :
204 * - destination is not onlink
205 * - preferred source address is set
206 * - output interface is UP
207 */
208 if (rt != NULL && !(rt->rt_flags & RTF_LLINFO) &&
209 !(rt->rt_flags & RTF_HOST)) {
210 ip6_source = rtable_getsource(rtableid, AF_INET6);
211 if (ip6_source != NULL) {
212 struct ifaddr *ifa;
213 if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) !=
214 NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) {
215 *in6src = &satosin6(ip6_source)->sin6_addr;
216 return (0);
217 }
218 }
219 }
220
221 if (ia6 == NULL)
222 return (EHOSTUNREACH); /* no route */
223
224 *in6src = &ia6->ia_addr.sin6_addr;
225 return (0);
226 }
227
228 /*
229 * Return an IPv6 address, which is the most appropriate for a given
230 * destination and multicast options.
231 * If necessary, this function lookups the routing table and returns
232 * an entry to the caller for later use.
233 */
234 int
in6_selectsrc(const struct in6_addr ** in6src,struct sockaddr_in6 * dstsock,struct ip6_moptions * mopts,unsigned int rtableid)235 in6_selectsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock,
236 struct ip6_moptions *mopts, unsigned int rtableid)
237 {
238 struct ifnet *ifp = NULL;
239 struct in6_addr *dst;
240 struct in6_ifaddr *ia6 = NULL;
241
242 dst = &dstsock->sin6_addr;
243
244 /*
245 * If the destination address is a link-local unicast address or
246 * a link/interface-local multicast address, and if the outgoing
247 * interface is specified by the sin6_scope_id filed, use an address
248 * associated with the interface.
249 * XXX: We're now trying to define more specific semantics of
250 * sin6_scope_id field, so this part will be rewritten in
251 * the near future.
252 */
253 if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) ||
254 IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) {
255 ifp = if_get(dstsock->sin6_scope_id);
256 if (ifp == NULL)
257 return (ENXIO); /* XXX: better error? */
258
259 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL);
260 if_put(ifp);
261
262 if (ia6 == NULL)
263 return (EADDRNOTAVAIL);
264
265 *in6src = &ia6->ia_addr.sin6_addr;
266 return (0);
267 }
268
269 /*
270 * If the destination address is a multicast address and
271 * the outgoing interface for the address is specified
272 * by the caller, use an address associated with the interface.
273 * Even if the outgoing interface is not specified, we also
274 * choose a loopback interface as the outgoing interface.
275 */
276 if (IN6_IS_ADDR_MULTICAST(dst)) {
277 ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL;
278
279 if (!ifp && dstsock->sin6_scope_id)
280 ifp = if_get(htons(dstsock->sin6_scope_id));
281
282 if (ifp) {
283 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL);
284 if_put(ifp);
285
286 if (ia6 == NULL)
287 return (EADDRNOTAVAIL);
288
289 *in6src = &ia6->ia_addr.sin6_addr;
290 return (0);
291 }
292 }
293
294 return (EADDRNOTAVAIL);
295 }
296
297 struct rtentry *
in6_selectroute(const struct in6_addr * dst,struct ip6_pktopts * opts,struct route * ro,unsigned int rtableid)298 in6_selectroute(const struct in6_addr *dst, struct ip6_pktopts *opts,
299 struct route *ro, unsigned int rtableid)
300 {
301 /*
302 * Use a cached route if it exists and is valid, else try to allocate
303 * a new one.
304 */
305 if (ro) {
306 struct rtentry *rt;
307
308 rt = route6_mpath(ro, dst, NULL, rtableid);
309
310 /*
311 * Check if the outgoing interface conflicts with
312 * the interface specified by ipi6_ifindex (if specified).
313 * Note that loopback interface is always okay.
314 * (this may happen when we are sending a packet to one of
315 * our own addresses.)
316 */
317 if (opts && opts->ip6po_pktinfo &&
318 opts->ip6po_pktinfo->ipi6_ifindex) {
319 if (rt != NULL && !ISSET(rt->rt_flags, RTF_LOCAL) &&
320 rt->rt_ifidx != opts->ip6po_pktinfo->ipi6_ifindex) {
321 return (NULL);
322 }
323 }
324
325 return (rt);
326 }
327
328 return (NULL);
329 }
330
331 int
in6_selectif(const struct in6_addr * dst,struct ip6_pktopts * opts,struct ip6_moptions * mopts,struct route * ro,struct ifnet ** retifp,u_int rtableid)332 in6_selectif(const struct in6_addr *dst, struct ip6_pktopts *opts,
333 struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp,
334 u_int rtableid)
335 {
336 struct rtentry *rt;
337 struct in6_pktinfo *pi = NULL;
338
339 /* If the caller specify the outgoing interface explicitly, use it. */
340 if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) {
341 *retifp = if_get(pi->ipi6_ifindex);
342 if (*retifp != NULL)
343 return (0);
344 }
345
346 /*
347 * If the destination address is a multicast address and the outgoing
348 * interface for the address is specified by the caller, use it.
349 */
350 if (IN6_IS_ADDR_MULTICAST(dst) &&
351 mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL)
352 return (0);
353
354 rt = in6_selectroute(dst, opts, ro, rtableid);
355 if (rt == NULL)
356 return (EHOSTUNREACH);
357
358 /*
359 * do not use a rejected or black hole route.
360 * XXX: this check should be done in the L2 output routine.
361 * However, if we skipped this check here, we'd see the following
362 * scenario:
363 * - install a rejected route for a scoped address prefix
364 * (like fe80::/10)
365 * - send a packet to a destination that matches the scoped prefix,
366 * with ambiguity about the scope zone.
367 * - pick the outgoing interface from the route, and disambiguate the
368 * scope zone with the interface.
369 * - ip6_output() would try to get another route with the "new"
370 * destination, which may be valid.
371 * - we'd see no error on output.
372 * Although this may not be very harmful, it should still be confusing.
373 * We thus reject the case here.
374 */
375 if (ISSET(rt->rt_flags, RTF_REJECT | RTF_BLACKHOLE))
376 return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
377
378 *retifp = if_get(rt->rt_ifidx);
379
380 return (0);
381 }
382
383 int
in6_selecthlim(const struct inpcb * inp)384 in6_selecthlim(const struct inpcb *inp)
385 {
386 if (inp && inp->inp_hops >= 0)
387 return (inp->inp_hops);
388
389 return (ip6_defhlim);
390 }
391
392 /*
393 * generate kernel-internal form (scopeid embedded into s6_addr16[1]).
394 * If the address scope of is link-local, embed the interface index in the
395 * address. The routine determines our precedence
396 * between advanced API scope/interface specification and basic API
397 * specification.
398 *
399 * this function should be nuked in the future, when we get rid of
400 * embedded scopeid thing.
401 *
402 * XXX actually, it is over-specification to return ifp against sin6_scope_id.
403 * there can be multiple interfaces that belong to a particular scope zone
404 * (in specification, we have 1:N mapping between a scope zone and interfaces).
405 * we may want to change the function to return something other than ifp.
406 */
407 int
in6_embedscope(struct in6_addr * in6,const struct sockaddr_in6 * sin6,const struct ip6_pktopts * outputopts6,const struct ip6_moptions * moptions6)408 in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6,
409 const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6)
410 {
411 u_int32_t scopeid;
412
413 *in6 = sin6->sin6_addr;
414
415 /*
416 * don't try to read sin6->sin6_addr beyond here, since the caller may
417 * ask us to overwrite existing sockaddr_in6
418 */
419
420 if (IN6_IS_SCOPE_EMBED(in6)) {
421 struct in6_pktinfo *pi;
422
423 /*
424 * KAME assumption: link id == interface id
425 */
426
427 if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) &&
428 pi->ipi6_ifindex)
429 scopeid = pi->ipi6_ifindex;
430 else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) &&
431 moptions6->im6o_ifidx)
432 scopeid = moptions6->im6o_ifidx;
433 else
434 scopeid = sin6->sin6_scope_id;
435
436 if (scopeid) {
437 struct ifnet *ifp;
438
439 ifp = if_get(scopeid);
440 if (ifp == NULL)
441 return ENXIO; /* XXX EINVAL? */
442 /*XXX assignment to 16bit from 32bit variable */
443 in6->s6_addr16[1] = htons(scopeid & 0xffff);
444 if_put(ifp);
445 }
446 }
447
448 return 0;
449 }
450
451 /*
452 * generate standard sockaddr_in6 from embedded form.
453 * touches sin6_addr and sin6_scope_id only.
454 *
455 * this function should be nuked in the future, when we get rid of
456 * embedded scopeid thing.
457 */
458 void
in6_recoverscope(struct sockaddr_in6 * sin6,const struct in6_addr * in6)459 in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6)
460 {
461 u_int32_t scopeid;
462
463 sin6->sin6_addr = *in6;
464
465 /*
466 * don't try to read *in6 beyond here, since the caller may
467 * ask us to overwrite existing sockaddr_in6
468 */
469
470 sin6->sin6_scope_id = 0;
471 if (IN6_IS_SCOPE_EMBED(in6)) {
472 /*
473 * KAME assumption: link id == interface id
474 */
475 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]);
476 if (scopeid) {
477 sin6->sin6_addr.s6_addr16[1] = 0;
478 sin6->sin6_scope_id = scopeid;
479 }
480 }
481 }
482
483 /*
484 * just clear the embedded scope identifier.
485 */
486 void
in6_clearscope(struct in6_addr * addr)487 in6_clearscope(struct in6_addr *addr)
488 {
489 if (IN6_IS_SCOPE_EMBED(addr))
490 addr->s6_addr16[1] = 0;
491 }
492